1. Field of the Invention
The present invention relates to an improved vertical form, fill and seal packaging machine. More specifically, the present invention relates to a vertical food packaging machine that forms a vacuum seal of the packaged food products.
2. Prior Art
It is often desirable to seal packaged food products under a vacuum. This is typically accomplished by sucking the air out of a package prior to it being sealed. Those skilled in the art will appreciate that this is generally time consuming and therefore slows packaging process significantly.
An alternative method of forcing air out of a food item package is to press foam about the package and then seal it. By pressing foam blocks on opposite sides of a package, air is forced out of the package and it may be sealed. However, this is undesirable because foam may retain water and become infested with bacteria. It is well known in the art that it is highly undesirable to use any materials during packaging capable of retaining bacteria. Brushes have also been used in place of foam but are also capable of retaining water.
It is therefore desirable to provide a method for rapid, sterile vacuum sealing of packaged food items.
The present invention relates to apparati and methods for making air tight bags or packages for use with a multiple purpose convertible vertical form, fill and seal machine and method for making a variety of styles or types of bags including overlap or fin seals, pillow, potato chip, non-reclosable or reclosable, product-filled bags and especially zipper lock reclosable bags.
Package or bag making machines generally referred to as vertical form, fill and seal machines and methods for manufacturing individual pillow type packages with non-reclosable, midline overlap longitudinal seams or seals are described, for example, U.S. Pat. No. 4,532,753 to Kovacs, granted Aug. 6, 1985 (U.S. Cl. 53/451); U.S. Pat. No. 4,768,327 to Mosher, granted Sep. 6, 1988 (U.S. Cl. 53/451); U.S. Pat. No. 4,965,986 to Klinkel, granted Oct. 30, 1990 (U.S. Cl. 53/551); U.S. Pat. No. 4,999,974 to Kovacs, et al., granted Mar. 19, 1991 (U.S. Cl. 53/434); and U.S. Pat. No. 5,279,098 to Fukuda, granted Jan. 18, 1994 (U.S. Cl. 53/451). Typically, a heat sealable web material is supplied from a roll and is guided to a former located at the upper end of the machine. The former folds the flat web material into a vertically oriented tube surrounding a tubular filling mandrel or pipe. The edges of the folded web material overlap one another, and, as the folded tube moves downwardly over the mandrel, the overlapped marginal edge portions are heat sealed to one another by a cyclicly operated longitudinal sealing mechanism. The web is thus formed into a web tube which is advanced through the machine in package length increments. As packages are formed by the machine, product is also filled into them by a feeder device located on top of the machine. The feeder device is driven in synchronism with the remainder of the machine and cyclicly discharges measured quantities or charges of product into the upper end of the filling mandrel. A transverse or end sealing mechanism below the filling mandrel forms package end seals in the web tube by cyclicly flattening the tube and heat sealing the two layers of the flattened tube to one another through the use of two relatively moving jaws which reciprocate toward and away from the web tube from the front and back of the machine. During one closing movement of the jaws, the sealing mechanism simultaneously forms the top end seal of the leading package and the bottom end seal of the following package, and it also cuts the web material between the two seals to separate the leading package from the web tube. Between successive operations of the jaws, the web tube is advanced in package length increments by vertically reciprocating the sealing jaws or by using intermittently operated feed belts.
In the above-mentioned patents, the midline longitudinal overlap or fin seam or seal is formed as the web material lays relatively flat against the product filling pipe or mandrel. Packaging machines which form longitudinal fin seams or seals while the edges of the web material extend outwardly from the product filling mandrel are described, for example, in U.S. Pat. Nos. 5,255,497 to Zoromski, et al., granted Oct. 26, 1993 (U.S. Cl. 53/551) and 4,691,499 to Umeda, et al., granted Sep. 8, 1987 (U.S. Cl. 53/451).
Vertical form, fill and seal machines and methods for making reclosable bags from a bag forming film and a separate plastic zipper element with edge fin seals which extend outwardly from the product fill pipe are described, for example, in U.S. Pat. Nos. 5,400,565 and 5,505,037 to Terminella, et al., granted Mar. 28, 1995 and Apr. 9, 1996, respectively (U.S. Cl. 53/133.4). The plastic zipper element is fed between the film edges and the film and zipper are joined by vertically oriented heated sealing bars. The thus formed and sealed tube is filled with product through the fill tube and horizontal cross-seals and cross-cutters complete the individual bags. In these machines, the vertical and horizontal seals are formed by sealing members or jaws which reciprocate toward and away from the plastic film from the right and left sides of the device.
Attempts have been made to provide a vertical form, fill and seal machine which produces more than one type of package.
Various zippered and zipper lock packages are seen in the following patents: U.S. Pat. No. 6,059,456, “Reclosable Profile Arrangement Using Slidable Closure Strip”, U.S. Pat. No. 5,924,173, “End Posts For Plastic Zipper”, U.S. Pat. No. 5,896,627, “High-strength Slide R For a Reclosable Bag”, U.S. Pat. No. 5,833,791, “Conforming End Stops For a Plastic Zipper”, U.S. Pat. No. 5,775,812, “Tamper-Evident Reclosable Plastic Bag With Breakaway Slide R”, U.S. Pat. No. 5,713,669, “Plastic Bag With Zipper Slide R Captured in Pocket”, and U.S. Pat. No. 5,669,715, “Tamper-Evident Reclosable Plastic Bag With Slide R”, the teachings of which are expressly incorporated by reference herein.